Integrated circuits have experienced continuous rapid growth due to constant improvements in the integration density of various electronic components (i.e., transistors, diodes, resistors, capacitors, etc.). For the most part, this improvement in integration density has come from repeated reductions in minimum feature size, allowing more components to be integrated into a given chip area.
A volume occupied by the integrated components is near the surface of the semiconductor wafer. Although dramatic improvements in lithography have resulted in considerable improvements in two-dimensional (2D) integrated circuit formation, there are physical limitations to the density that can be achieved in two dimensions. One of these limitations is the minimum size needed to make these components. Further, when more devices are put into one chip, more complex designs are required. An additional limitation comes from the significant gains in the number and length of interconnections between devices as the number of devices increases. When the number and length of interconnections increase, both circuit RC delay and power consumption increase. Three-dimensional integrated circuits (3DIC) were thus proposed, wherein dies are stacked, with wire-bonding, flip-chip bonding, and/or through-silicon vias (TSV) being used to stack the dies together and to connect the dies to package substrates.
Memories, either volatile or nonvolatile, are among the most widely used cores in current three-dimensional integrated circuit (3DIC) implementations. Memories can exist as memory dies to be integrated with separate logic dies or exist as embedded memories to be part of logic dies. Advanced memory dies and embedded memory devices both have high device densities and occupy large chip areas. A probability that a defect lies within a memory die or embedded memory is relatively high. The memory die or embedded memory thus becomes a controlling factor in die yield. 3DIC manufacturing involves packaging of dies and bonding of packaged dies. The packaging and bonding processes impact the yield of final product.